This invention relates to an electronic control apparatus of an automatic speed changing apparatus for use in power driven vehicles utilizing a fluid type torque converter (for the sake of brevity, hereinafter merely called a torque converter) and a multiple stage gear type speed changer.
In automatic speed changing apparatus heretofore been used for power driven vehicles the speed changing point is determined by a car speed signal or in accordance with the number of revolutions of an internal combustion engine and a negative suction pressure of the engine or the degree of depressing an acceleration pedal (throttle opening). More particularly, signals representing these parameters are converted into variations in oil pressure or electric signals, and the speed changing point is determined by the relative relation between these oil pressure variations or electric signals for opening and closing a fuel value and for selectively actuating an actuator for multiple disc type clutch. Where detection signals are produced in terms of the oil pressure variations, the oil pressure acting as the detection signals are not always accurate thus causing an error of the speed changing point. For the purpose of obviating this difficulty, a system has been developed in which detection signals are produced in the form of electric signals. In this system, the degree of depression of the acceleration pedal, the slip of the torque converter, and the number of revolutions of the engine corresponding to the car speed are detected for effecting automatic speed changing, but the construction of the apparatus is complicated because there are many parameters to be detected.